The invention relates to an arrangement for locking the steering shaft of a steering device of a motor vehicle.
An arrangement of this nature is known, for example, from DE 197 19 343 C1. In this arrangement, the steering shaft is locked by a blocking device which comprises a blocking element which is arranged in such a manner that it can be displaced from an unlocked position into a locked position by means of an electric motor and which in its locked position engages in the recess, formed by adjacent teeth, in a toothed ring arranged on the outer circumference of the steering shaft. This known arrangement does not provide any further details concerning the way in which the blocking device is attached to the steering device.
DE 44 22 467 C1 has also disclosed a locking arrangement of the generic type, in which the blocking device includes a lever-like blocking element which can be pivoted by means of a magnet. The blocking device and the toothed ring, which is attached to the steering shaft, are situated in a common housing which is guided around the steering shaft of the vehicle. To prevent unauthorized third parties from interfering with the locking arrangement, that end of the blocking element which is remote from the toothed ring engages in a groove-like recess in the housing when the blocking element has pivoted into its locked position, thus preventing the housing from opening.
One of the drawbacks of this locking arrangement is that the blocking device takes a relatively long time to fit and remove, since the housing arranged on the steering shaft has to be opened to do this.
The invention is based on the object of providing an arrangement of the type described at the outset in which the blocking device can both be attached in a simple manner to the steering device of the vehicle in question and exchanged quickly, while ensuring that it is impossible to remove the blocking device in the locked state of the blocking element.
According to the invention, this object is achieved by means of the features of claim 1. Further, particularly advantageous configurations of the invention are disclosed by the subclaims.
The invention is fundamentally based on the principle of releasably connecting the blocking device, which is provided with a housing, to a flange, which is attached to the steering device, via an adapter part which is assigned to the blocking device and serves as a blocking-pin guide. The flange has a recess which is designed in such a manner that the adapter part, in order for the blocking device to be fitted, can be inserted in a first partial area of the recess and can then be displaced along a guide into its limit position, in which the blocking element is situated above the toothed ring area into which it is to engage when used correctly. Moreover, transverse webs are arranged between the teeth of the toothed ring, which webs, in the locked position of the blocking element, prevent axial displacement of the adapter part along the recess in the flange to the first partial area, so that the blocking device cannot be removed by unauthorized third parties in the locked position of the blocking element.
In an advantageous embodiment of the invention, the adapter part is designed with grooves which are arranged in the shape of a trapezoid in the direction of the steering shaft axis and which engage in a recess in the flange, which is likewise in the shape of a trapezoid. The trapezoidal arrangement of the attachment grooves in the adapter part ensures that, during fitting, the flanks of the attachment flange come to bear against the corresponding groove base of the adapter part, even if manufacturing tolerances cause the component dimensions to vary within defined limits. Consequently, the adapter part rests without play in the recess in the flange, so that in the event of loads being applied to the locked blocking pin as a result of a torque being applied to the steering shaft, there are no tolerances which have to be overcome by shifting the adapter part before the force flux from the blocking pin via the adapter part onto the frame parts of the steering shaft is closed.
Furthermore, it has proven advantageous if, for releasably connecting the adapter part on the flange, there is an attachment screw, which extends in the axial direction and, when this screw is tightened, the adapter part is at the same time displaced into its limit position. The attachment screw may be designed as a cap screw and may be guided through the adapter part and engage in a threaded part arranged on the flange.